One-step detection of miRNA-21 cancer marker in serum using molecularly imprinted nanoparticle recognition and surface plasmon resonance

Background

The rapid one step detection of cancer markers at early stages of cancer is critical to increase the efficiency of the treatments and survival. miRNA-21 is the most commonly upregulated microRNA in solid tumours and haematological malignancies and is associated with poor prognosis and survival rate. Therefore, its detection at the early stage is vital, ideally using a rapid, simple method with a low detection limit. Current methods often require sophisticated method and labelling to detect miRNAs.

Results

Here, we show that nanosized molecularly imprinted polymers (nanoMIPs), can selectively and sensitively detect miRNA-21 without labelling. NanoMIPs were synthesized via solid-phase polymerization. The template molecule of 5’ phosphor-capped miRNA-21 was attached to a functionalised glass bead via phosphorylimidazolide chemistry. Selected functional monomers/cross-linkers were used to generate selective nanoMIPs with recognition based on electrostatic and ionic interactions. NanoMIPs were characterized to investigate their physicochemical properties and interaction with target molecule. These nanoMIPs were then used for miRNA-21 detection studies exploring affinity and selectivity to the target with Surface Plasmon Resonance in both buffer and serum. High affinity materials (equilibrium dissociation constants – KD’ s in the nM/pM range) were demonstrated with high selectivity and when linked to the SPR sensor, a theoretical lower detection limit (LOD) of miRNA-21 was calculated as 0.49 pM in serum.

Significance

This work provides new perspectives in developing miRNA-21 specific synthetic molecular recognition materials using nanoMIPs. The nanoMIPs has potential to be suitable sensor platform, that could be promising tools for early cancer diagnostics in complex matrices.